Some adults may question whether they have attention deficit hyperactivity disorder or wonder if their ADHD-like behaviors – inattention, hyperactive-impulsivity or a combination of the two – are simply a product of the overwhelming, hurried demands of adulthood. How can you know for sure? A telltale sign that an adult has ADHD is when behaviors begin to interfere with life at home or in the workplace, says Stephanie Sarkis, an author and psychotherapist located in Tampa, Florida.